Fixing poetry major.minor compatibility

Adding a test to ensure we don't update the pyproject.toml with a new python version, but temporarily we expand the range to allow the update to proceed.

python/lib/dependabot/python/file_updater/poetry_file_updater.rb

@@ -106,6 +106,7 @@ def prepared_pyproject
               content = sanitize(content)
               content = freeze_other_dependencies(content)
               content = freeze_dependencies_being_updated(content)
+              content = update_python_requirement(content)
               content
             end
         end
@@ -131,6 +132,12 @@ def freeze_dependencies_being_updated(pyproject_content)
           TomlRB.dump(pyproject_object)
         end
 
+        def update_python_requirement(pyproject_content)
+          PyprojectPreparer.
+            new(pyproject_content: pyproject_content).
+            update_python_requirement(Helpers.python_major_minor(python_version))
+        end
+
         def lock_declaration_to_new_version!(poetry_object, dep)
           Dependabot::Python::FileParser::PyprojectFilesParser::POETRY_DEPENDENCY_TYPES.each do |type|
             names = poetry_object[type]&.keys || []

python/lib/dependabot/python/file_updater/pyproject_preparer.rb

@@ -36,6 +36,14 @@ def add_auth_env_vars(credentials)
           end
         end
 
+        def update_python_requirement(requirement)
+          pyproject_object = TomlRB.parse(@pyproject_content)
+          if pyproject_object.dig("tool", "poetry", "dependencies", "python")
+            pyproject_object["tool"]["poetry"]["dependencies"]["python"] = "~#{requirement}"
+          end
+          TomlRB.dump(pyproject_object)
+        end
+
         def sanitize
           # {{ name }} syntax not allowed
           pyproject_content.

python/spec/dependabot/python/file_updater/poetry_file_updater_spec.rb

@@ -80,7 +80,7 @@
         to start_with("8cea4ecb5b2230fbd4a33a67a4da004f1ccabad48352aaf040")
     end
 
-    context "with a specified Python version", :slow do
+    context "with a specified Python version" do
       let(:pyproject_fixture_name) { "python_310.toml" }
       let(:lockfile_fixture_name) { "python_310.lock" }
 
@@ -112,6 +112,11 @@
         requests = lockfile_obj["package"].find { |d| d["name"] == "requests" }
         expect(requests["version"]).to eq("2.19.1")
       end
+      it "does not change python version" do
+        updated_pyproj = updated_files.find { |f| f.name == "pyproject.toml" }
+        pyproj_obj = TomlRB.parse(updated_pyproj.content)
+        pyproj_obj["tool"]["poetry"]["dependencies"]["python"] == "3.10.7"
+      end
     end
 
     context "with a supported python version", :slow do